Tough, flexible tubing is useful in many commercial and industrial applications. Such tubing can be pinched off for a long period of time, or compressed thousands of times, yet quickly regain its original shape. The tubing must not lose flexibility, nor crack or break in use.
Many applications and manufacturing processes require tubing that is not only tough and flexible—but is also chemically and biologically inert. The inside surface of such tubing must be non-reactive with the fluid (liquid or gas) passing through it, have excellent barrier properties, and should have little or no extractables.
Current tubing technology used in biopharmaceutical applications, for example, includes silicone, thermoplastic polyolefins (TPO), thermoplastic polyethylene (TPE), and expanded PTFE composite tubing.
One of the applications of the tubing is for use in peristaltic pumps. Peristaltic pumps are non-contact positive displacement pumps used for transferring fluids. The transfer of the fluid is generated by successive compression of the walls of the tube, creating pressure to transfer the fluid. This application needs a tube with excellect memory and recovery properties. For these applications, there is a need for a high purity, chemically resistant tube with good barrier properties. Peristaltic pumps are useful in the transfer of chemicals and biopharmaceutical materials, where the fluid does not contact the pump.
Polyvinylidene fluoride (PVDF) is known for its high chemical resistant and inertness. Unfortunately, PVDF does not possess the high flexibility and restitution needed to withstand the rigorous cycles of a peristaltic pump.
Surprisingly it has been found that a multi-layer tube having a thin layer of PVDF as the fluid contact layer having one or more layers of flexible polymer outside fulfill the requirements for a peristaltic pump application. Currently, there are no products in the market that can match the balance of properties of the tubes of the invention in terms of the contact layer purity, chemical resistance and barrier properties, combined with the flexibility and restitution (or spring back) of the overall structure.